Rotary piston internal combustion engine

ABSTRACT

A rotary piston internal combustion engine especially of trochoidal construction with a piston that is provided at its corners with sealing bars which, for purposes of increasing the adaptability to the running surface of the casing, is constructed flexible, particularly elastic in bending by a selective reduction of its height, primarily in its center part.

United States Patent 91 Lamm [ 1 Feb. 13, 1973 1 ROTARY PISTON INTERNAL COMBUSTION ENGINE [75] Inventor: Heinz Lamm, Esslingen-St. Bemhardt, Germany [73] Assignee: Daimler-Beni Aktiengesellschaft, Stuttgart-Untertuerkheim,Germany 22 Filed: May 15,1970

211 Appl.No.: 37,676

[30] Foreign Application Priority Data May 16, 1969 Germany ..P 19 25 019.2

[52] US. Cl ..418/121, 418/122 51] Int. Cl ..FOlc 19/02, F031: 3/00, F04C 27/00 [58] Field of Search ..418/113,l14,115,1l6,120, 418/121,122,123,l24,143, 144, 266, 267, 268, 269; 277/81 P [56] v References Cited UNITED STATES PATENTS 3,270,954 9/1966 Yamamoto ..418/61 3,369,738 2/1968 Rottmann ..418/122 3,286,912 11/1966 Tado ..418/120 3,400,691 9/1968 Jones ..418/121 X 3,120,815 2/1964 Froede ..418/123 X 3,180,564 4/1965 Fuhrmann et al. ..418/122 X 3,556,695 1/1971 Yamamoto ..418/122 X FOREIGN PATENTS OR APPLICATIONS 1,223,612 8/1966 Germany ..277/81 R Primary ExaminerCarlton R. Croyle Assistant Examiner-John J. Vrablik Attomey-Craig, Antonelli, Stewart & Hill ABSTRACT A rotary piston internal combustion engine especially of trochoidal construction with a piston that is provided at its comers with sealing bars which, for purposes of increasing the adaptability to the running surface of the casing, is constructed flexible, particularly elastic in bending by a selective reduction-of its height, primarily in its center part.

17 Claims, 5 Drawing Figures ROTARY PISTON INTERNAL COMBUSTION ENGINE The present invention relates to a rotary piston internal combustion engine particularly of trochoidal construction with a piston that is provided with sealing bars at its corners.

The present-day sealing bar constructions have a rectangular cross section which, for example, with a unitary sealing bar, i.e., made-in onepiece, remains uniformly constant in cross section over its length. In order to achieve the necessary gas-tightness with respect to the contact or running surface,- a certain adaptation of the sealing bar to the macro structure of the running or contact surface of the casing is necessary.

The present invention is concerned with the task to construct the sealing bars in such a manner that they can adapt themselves in the best possible manner to their contact or running surface.

The underlying problems are solved according to the present invention in that the sealing bars for the purpose of increasing their adaptability to the running or contact surface are constructed flexible or elastic in bending by a reduction in certain places in the height thereof primarily in the center part thereof.

It is advantageously achieved thereby that unevennesses in the macro structure of the casing running surface are compensated for by the bending-elastic or flexible deformations of the sealing bars. A larger throughbending or deflection of the sealing bar is made possible by the smaller inertia moment primarily in the sealing bar center. By reason of the fact that the sealing bar is lower in its center portion, a more rapid gas admission is made possible underneath the sealing bar, and in this manner additional grooves in the lower portion of the sealing bar may be dispensed with, which otherwise would possibly be necessary on the leading side. Advantageous is also the weight-saving of the sealing bar. The sealing bar flanks are elastic and act springily so that a wedging or jamming in the piston groove cannot occur. Notwithstanding the differing height, the necessary guidance with respect to the piston groove remains preserved at both ends of the sealing bar.

In one preferred type of construction according to t the present invention, the sealing-bar may be provided with 21 preferably symmetrical recess extending over a large portion of its length and starting from the bottom side. The height of the recess is so selected that not withstanding the stroke movement and wear of the sealing bar, a gas-tightness is always assured.

The present invention proposes that the recess has a cross section which is either in the form of a circular are or of a rectangle.

According to a further feature of the present invention, the recess or aperture may extend over the entire width or only over a part of the width. If a rapid gas entry underneath the sealing bar is desirable for only one sealing bar side, then the recess or aperture may be provided, for example, only on one flank.

For the further increase of the elasticity of the sealing bar, there may be additionally provided a slot extending from the bottom side of the sealing bar and arranged preferably in the center of its cross section over the entire length thereof, whose width corresponds approximately to one-third of the width of the sealing bar and whose height is smaller by approximately the same value than the over-all height of the sealing bar. The elastic leg portions of the sealing bar, which adapt themselves springily, produce a greater gas-tightness during the abutment at the groove wall.

According to another type of construction in accordance with the present invention, the sealing bar may be constructed as a three-partite sealing bar with a center part and corner parts and the recess may be provided only in the center part.

Accordingly, it is an object of the present invention to provide a rotary piston internal combustion engine with a piston equipped with sealing bars in the corners thereof which avoids by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

. Another object of the present invention resides in a sealing bar which is so constructed that it offers optimum adaptability to the running or contact surface.

A further object of the present invention resides in a sealing bar which is constructed flexible or elastic in bending primarily in the center part thereof.

Still a further object of the present invention resides in a sealing bar for a rotary piston internal combustion engine which permits a ready compensation for unevennesses in the macro structure of the contact surface of the casing.

A still further object of the present invention resides in a sealing bar which not only enables a more rapid gas admission underneath the sealing bar butalso results in a more simple construction accompanied by saving in weight and ease of manufacture.

- Another object of the present invention resides in a sealing bar which prevents jamming of the bar in the piston groove, yet assures a completely satisfactory gastightness even in the presence of some wear.

These and further objects, features, and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention, and wherein:

FIG. 1 is an elevational view of a sealing bar for the corners of a piston of a rotary piston internal combustion engine in accordance with the present invention;

FIG. 2 is a transverse cross-sectional view taken along line IIII of FIG. 1',

FIG. 3 is a transverse cross-sectional view, similar to FIG. 2, of a modified embodiment of the sealing bar in accordance with the present invention;

FIG. 4is an elevational view, similar to FIG. 1, illustrating a modified embodiment of a sealing bar for the corners of a piston of a rotary piston internal combustion engine in accordance with the present invention, and

FIG. 5 is a partial schematic cross-sectional view through a rotary piston internal combustion engine of trochoidal construction.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts and more particularly to FIG. 1, reference numeral 1 generally designates in this figure a sealing bar in longitudinal view provided with an arcuately shaped recess 2 which is arranged symmetrically to the center thereof extending over nearly the entire length of the sealing bar 1 and starting from the bottom side 3 thereof, and with a slot 4 whichas can be readily seen from FIG. 2is provided in the center of the cross section of the sealing bar 1 extending in the longitudinal direction of the sealing bar 1 and also starting from the bottom side 3 thereof. The depth of the slot 4 amounts approximately to two-thirds of the height of the sealing bar 1 and its width is approximately a third of the entire width of the sealing bar 1 as also shown in FIG. 2. The sealing bar 1 is separated from two essentially triangularly shaped end sections 5 and 6 whereby the respective planes of separation are disposed perpendicular to the figure and at an acute angle to the longitudinal axis of the sealing bar 1; the triangularly shaped sections 5 and 6 are provided with extensions 7 and 8 for the support of the sealing bar spring (indicated schematically in dash and dot lines). The extensions 7 and 8 form together with the bottom surfaces 5' and 6' the abutment surfaces for such spring urging the sealing bar into engagement with the running surface 21 (FIG. 5) of the casing generally designated by reference numeral 20. The radius 9 of the sealing bar head portion 10 is, as can also be seen from FIG. 2, larger than half the width of the sealing bar 1.

FIG. 2 illustrates a cross section through the center portion generally designated by reference numeral 11 of the sealing bar 1 illustrated in FIG. 1.

FIG. 3 illustrates the center portion 11 of a modified embodiment of a sealing bar 1 in cross section with a slot 12 extending in the center of the cross section and starting from the bottom side 3, whose width corresponds approximately to one-third of the width of the sealing bar 1 and whose height is smaller by approximately the same amount than the full height of the sealing bar 1. The sealing bar 1 of FIG. 3 is also provided in its center portion 11 with one recess 2 in the leading leg portion 14 of the sealing bar 1 as viewed in the direction of rotation 13, whose height is smaller than the height of the slot 12. The radius 9 of the sealing bar head portion 10 is larger than half the width of the sealing bar 1.

FIG. 4 illustrates a modified embodiment in accordance with the present invention in which the sealing bar generally-designated by reference numeral 1 is again provided with a spring recess defined by the extension 7' and abutment surfaces 5 and 6'. In this embodiment a further recess 2 is provided of substantially rectangular configuration as viewed in FIG. 4 which produces the bending elastic characteristic of the bar. Otherwise, the bar of FIG. 4, corresponds to that of FIG. 1.

FIG. 5 schematically illustrates a partial cross-sectional view through a rotary piston internal combustion engine of trochoidal construction which includes a casing generally designated by reference numeral provided with an internal running surface 21 along which slide the sealing bars 1, provided in the grooves 23 of the piston corners, as the piston 22 rotates.

While I have shown and described two embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art. For example, the various features described hereinabove, illustrated in the drawing and set forth in the appended claims may be utilized either individually or also in any desired combination with each other for realizing the present invention. Consequently, I do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

Iclaim:

l. A rotary piston internal combustion engine comprising a casing having a contact surface, a polygonal piston provided at its corners with grooves, springloaded sealing bars sliding within the grooves of the piston and having longitudinal ends and rectilinear top sealing surfaces unitary with the sealing bars and engaging at the contact surface, the sealing bars being provided at the bottom side thereof with a recess forming near the longitudinal ends of a bar abutment surfaces, springs for spring loading the bars having ends directly engaging the abutment surfaces, said abutment surfaces extending substantially parallel to the top sealing surfaces of a sealing bar, characterized in that the sealing bars are of unitary construction at least in the center portion thereof containing said rectilinear top sealing surfaces andhave means providing smaller inertia moments primarily in said center portion thereof and resulting in a sealing bar which is elastic in bending for increasing the adaptability thereof to the contact surface, said means being constituted by a reduction in overall height thereof at least in the center portion of a unitary bar in the form of a further recess, which is sufficient to substantially affect the elasticity in bending of the sealing bar, said reduction being in addition to said first-mentioned recess and beginning from a level of a bar corresponding to the spacing of the abutment surfaces from the bottom of the sealing bar, said further recess extending over a large portion of the length of a sealing bar and starting from said first-mentioned recess.

2. A rotary piston internal combustion engine according to claim 1, characterized in that the engine is of trochoidal construction.

3. A rotary piston internal combustion engine according to claim 1, characterized in that the further recess extends over at least a part of the width of the sealing bar.

4. A rotary piston internal combustion engine according to claim 1, characterized in that the further recess extends over the entire width of the sealing bar.

5. A rotary piston internal combustion engine according to claim 1, characterized in that the further recess extends only over a portion of the width of the sealing bar.

6. A rotary piston internal combustion engine according to claim 1, characterized in that said further recess is substantially symmetrical to the center of a bar.

7. A rotary piston internal combustion engine according to claim 6, characterized in that the further recess has a cross section substantially in the form of a circular arc.

8. A rotary piston internal combustion engine according to claim 6, characterized in that the further recess has a cross section which is substantially rectangular.

9. A rotary piston internal combustion engine according to claim 1, characterized in that a slot is provided additionally extending from the bottom side of the sealing bar, the width of said slot corresponding to about one-third the width of the sealing bar and the height thereof being less by approximately the same amount than the over-all height of the sealing bar.

10. A rotary piston internal combustion engine according to claim 9, characterized in that said slot extends substantially in the center of the cross section of the sealing bar.

11. A rotary piston internal combustion engine according to claim 10, characterized in that said slot extends substantially over the entire length of the sealing bar.

12. A rotary piston internal combustion engine according to claim 11, characterized in that the sealing bar includes a center portion and corner sections, the recess being provided only in the center section.

13. A rotary piston internal combustion engine according to claim 12, characterized in that the center portion is separated from said end sections in separating planes extending at an acute angle to the longitudinal direction of the sealing bar.

14. A rotary piston internal combustion engine according to claim 1, characterized in that the top surfaces of the sealing bars are generally straight in the longitudinal direction thereof while the reductions in height are effected by decreases in the dimensions from the top surfaces and amount at least in the center thereof to more than half the height of the non-reduced parts of the sealing bars.

15. A rotary piston internal combustion engine according to claim 14, characterized in that the reductions in height vary continuously at least over nearly the entire length of a sealing bar in the form of an arc having its center underneath a sealing bar.

16. A rotary piston internal combustion engine according to claim 14, characterized in that the sealing bars are veach provided with a longitudinally extending recess starting from the bottom to a depth of about two-thirds of the height of the non-reduced portions of the sealing bar and in that the reduction in height in the center of the sealing baris slightly less than the depth of longitudinally extending recesses.

17. A rotary piston internal combustion engine according to claim 16, characterized in that the reductions in height vary continuously at least over nearly the entire length of a sealing bar in the form of an are having its center underneath a sealing bar. 

1. A rotary piston internal combustion engine comprising a casing having a contact surface, a polygonal piston provided at its corners with grooves, spring-loaded sealing bars sliding within the grooves of the piston and having longitudinal ends and rectilinear top sealing surfaces unitary with the sealing bars and engaging at the contact surface, the sealing bars being provided at the bottom side thereof with a recess forming near the longitudinal ends of a bar abutment surfaces, Springs for spring loading the bars having ends directly engaging the abutment surfaces, said abutment surfaces extending substantially parallel to the top sealing surfaces of a sealing bar, characterized in that the sealing bars are of unitary construction at least in the center portion thereof containing said rectilinear top sealing surfaces and have means providing smaller inertia moments primarily in said center portion thereof and resulting in a sealing bar which is elastic in bending for increasing the adaptability thereof to the contact surface, said means being constituted by a reduction in overall height thereof at least in the center portion of a unitary bar in the form of a further recess, which is sufficient to substantially affect the elasticity in bending of the sealing bar, said reduction being in addition to said first-mentioned recess and beginning from a level of a bar corresponding to the spacing of the abutment surfaces from the bottom of the sealing bar, said further recess extending over a large portion of the length of a sealing bar and starting from said first-mentioned recess.
 1. A rotary piston internal combustion engine comprising a casing having a contact surface, a polygonal piston provided at its corners with grooves, spring-loaded sealing bars sliding within the grooves of the piston and having longitudinal ends and rectilinear top sealing surfaces unitary with the sealing bars and engaging at the contact surface, the sealing bars being provided at the bottom side thereof with a recess forming near the longitudinal ends of a bar abutment surfaces, Springs for spring loading the bars having ends directly engaging the abutment surfaces, said abutment surfaces extending substantially parallel to the top sealing surfaces of a sealing bar, characterized in that the sealing bars are of unitary construction at least in the center portion thereof containing said rectilinear top sealing surfaces and have means providing smaller inertia moments primarily in said center portion thereof and resulting in a sealing bar which is elastic in bending for increasing the adaptability thereof to the contact surface, said means being constituted by a reduction in overall height thereof at least in the center portion of a unitary bar in the form of a further recess, which is sufficient to substantially affect the elasticity in bending of the sealing bar, said reduction being in addition to said first-mentioned recess and beginning from a level of a bar corresponding to the spacing of the abutment surfaces from the bottom of the sealing bar, said further recess extending over a large portion of the length of a sealing bar and starting from said first-mentioned recess.
 2. A rotary piston internal combustion engine according to claim 1, characterized in that the engine is of trochoidal construction.
 3. A rotary piston internal combustion engine according to claim 1, characterized in that the further recess extends over at least a part of the width of the sealing bar.
 4. A rotary piston internal combustion engine according to claim 1, characterized in that the further recess extends over the entire width of the sealing bar.
 5. A rotary piston internal combustion engine according to claim 1, characterized in that the further recess extends only over a portion of the width of the sealing bar.
 6. A rotary piston internal combustion engine according to claim 1, characterized in that said further recess is substantially symmetrical to the center of a bar.
 7. A rotary piston internal combustion engine according to claim 6, characterized in that the further recess has a cross section substantially in the form of a circular arc.
 8. A rotary piston internal combustion engine according to claim 6, characterized in that the further recess has a cross section which is substantially rectangular.
 9. A rotary piston internal combustion engine according to claim 1, characterized in that a slot is provided additionally extending from the bottom side of the sealing bar, the width of said slot corresponding to about one-third the width of the sealing bar and the height thereof being less by approximately the same amount than the over-all height of the sealing bar.
 10. A rotary piston internal combustion engine according to claim 9, characterized in that said slot extends substantially in the center of the cross section of the sealing bar.
 11. A rotary piston internal combustion engine according to claim 10, characterized in that said slot extends substantially over the entire length of the sealing bar.
 12. A rotary piston internal combustion engine according to claim 11, characterized in that the sealing bar includes a center portion and corner sections, the recess being provided only in the center section.
 13. A rotary piston internal combustion engine according to claim 12, characterized in that the center portion is separated from said end sections in separating planes extending at an acute angle to the longitudinal direction of the sealing bar.
 14. A rotary piston internal combustion engine according to claim 1, characterized in that the top surfaces of the sealing bars are generally straight in the longitudinal direction thereof while the reductions in height are effected by decreases in the dimensions from the top surfaces and amount at least in the center thereof to more than half the height of the non-reduced parts of the sealing bars.
 15. A rotary piston internal combustion engine according to claim 14, characterized in that the reductions in height vary continuously at least over nearly the entire length of a seAling bar in the form of an arc having its center underneath a sealing bar.
 16. A rotary piston internal combustion engine according to claim 14, characterized in that the sealing bars are each provided with a longitudinally extending recess starting from the bottom to a depth of about two-thirds of the height of the non-reduced portions of the sealing bar and in that the reduction in height in the center of the sealing bar is slightly less than the depth of longitudinally extending recesses. 